Ceph 出现pg object unfound的处理经过
原文链接：https://my.oschina.net/xiaozhublog/blog/3075404
1、背景
集群中的一个节点损坏，同时另外一个节点坏了一块盘
2、问题
查看ceph集群的状态，看到归置组pg 4.210丢了一个块
# ceph health detail
HEALTH_WARN 481/5647596 objects misplaced (0.009%); 1/1882532 objects unfound (0.000%); Degraded data redundancy: 965/5647596 objects degraded (0.017%), 1 pg degraded, 1 pg undersized
OBJECT_MISPLACED 481/5647596 objects misplaced (0.009%)
OBJECT_UNFOUND 1/1882532 objects unfound (0.000%)pg 4.210 has 1 unfound objects
PG_DEGRADED Degraded data redundancy: 965/5647596 objects degraded (0.017%), 1 pg degraded, 1 pg undersizedpg 4.210 is stuck undersized for 38159.843116, current state active+recovery_wait+undersized+degraded+remapped, last acting [2]
3、处理过程
3.1、先让集群可以正常使用
查看pg 4.210，可以看到它现在只有一个副本
# ceph pg dump_json pools |grep 4.210
dumped all
4.210 482 1 965 481 1 2013720576 3461 3461 active+recovery_wait+undersized+degraded+remapped 2019-07-10 09:34:53.693724 9027'1835435 9027:1937140 [6,17,20] 6 [2] 2 6368'1830618 2019-07-07 01:36:16.289885 6368'1830618 2019-07-07 01:36:16.289885 2
# ceph pg map 4.210
osdmap e9181 pg 4.210 (4.210) -> up [26,20,2] acting [2]
丢了两个副本，而且最主要的是主副本也丢了…
因为默认指定的pool的min_size为2，这就导致4.210所在的池vms不能正常使用
# ceph osd pool stats vms
pool vms id 4965/1478433 objects degraded (0.065%)481/1478433 objects misplaced (0.033%)1/492811 objects unfound (0.000%)client io 680 B/s rd, 399 kB/s wr, 0 op/s rd, 25 op/s wr
# ceph osd pool ls detail|grep vms
pool 4 'vms' replicated size 3 min_size 2 crush_rule 0 object_hash rjenkins pg_num 1024 pgp_num 1024 last_change 10312 lfor 0/874 flags hashpspool stripe_width 0 application rbd
直接影响了部分虚拟机，导致部分虚拟机夯住了，执行命令无回应
为了可以正常使用，先见vms池的min_size调整为1
# ceph osd pool set vms min_size 1
set pool 4 min_size to 1
3.2、尝试恢复pg4.210丢失的块
查看pg4.210
# ceph pg 4.210 query "recovery_state": [{"name": "Started/Primary/Active","enter_time": "2019-07-09 23:04:31.718033","might_have_unfound": [{"osd": "4","status": "already probed"},{"osd": "6","status": "already probed"},{"osd": "15","status": "already probed"},{"osd": "17","status": "already probed"},{"osd": "20","status": "already probed"},{"osd": "22","status": "osd is down"},{"osd": "23","status": "already probed"},{"osd": "26","status": "osd is down"}]
字面上理解，pg 4.210的自我恢复状态，它已经探查了osd4、6、15、17、20、23,osd22和26已经down了，而我这里的osd22和26都已经移出了集群
根据官网了解到此处might_have_unfound的osd有以下四种状态
already probed
querying
OSD is down
not queried (yet)
两种解决方案，回退旧版或者直接删除
# ceph pg 4.210 mark_unfound_lost revert
Error EINVAL: pg has 1 unfound objects but we haven't probed all sources,not marking lost
# ceph pg 4.210 mark_unfound_lost delete
Error EINVAL: pg has 1 unfound objects but we haven't probed all sources,not marking lost
提示报错，pg那个未发现的块还没有探查所有的资源，不能标记为丢失，也就是不会回退也不可以删除
猜测可能是已经down的osd22和26未探查，刚好坏的节点也重装完成，重新添加osd
osd的删除添加过程此处不赘述了。
添加完成后，再次查看pg 4.210
"recovery_state": [{"name": "Started/Primary/Active","enter_time": "2019-07-15 15:24:32.277667","might_have_unfound": [{"osd": "4","status": "already probed"},{"osd": "6","status": "already probed"},{"osd": "15","status": "already probed"},{"osd": "17","status": "already probed"},{"osd": "20","status": "already probed"},{"osd": "22","status": "already probed"},{"osd": "23","status": "already probed"},{"osd": "24","status": "already probed"},{"osd": "26","status": "already probed"}],"recovery_progress": {"backfill_targets": ["20","26"],
可以看到所有的资源都probed了，此时执行回退命令
# ceph pg 4.210 mark_unfound_lost revert
pg has 1 objects unfound and apparently lost marking
查看集群状态
# ceph health detail
HEALTH_OK
恢复池vms的min_size为2
# ceph osd pool set vms min_size 2
set pool 4 min_size to 2
参考链接
http://www.itzhoulin.com/2016/04/20/object-unfound-when-wrong-steps-in-ceph-full/http://docs.ceph.com/docs/master/rados/troubleshooting/troubleshooting-pg/?highlight=troubleshoot